Spectral sequence illustrating the spectral evolution of SN 2019zrk. The early P200 spectrum at 8 days (red) revealed a Type IIn SN with a blue continuum and superimposed narrow emission lines. A month later, the deep Keck spectrum (black) instead shows a broad and asymmetric line profile of Hα, which typically reflects strong CSM interaction. Finally, the day 83 and 109 NOT spectra display increasingly strong P-Cygni absorption features. The dashed lines for each spectrum show blackbody fits to the continuum (see text). For clarity some of the spectra have been shifted by the logarithmic factor provided together with the phase in the figure. All spectra are corrected for the Milky Way extinction.